Polymerizable compound-containing liquid crystal composition and liquid crystal display device using the same

ABSTRACT

A polymerizable compound-containing liquid crystal composition of the present invention relates to a liquid crystal composition containing a polymerizable compound represented by general formula (I) and a compound represented by general formula (II) and can be used for a liquid crystal display device imparted with liquid crystal aligning ability by polymerization. The polymerizable liquid crystal composition is required to cause no precipitation in a wide temperature range and have a low viscosity corresponding to fast switching, and a liquid crystal display device using the composition is required to have more stable alignment after polymerization and to cause no defect in display characteristics. In the present invention, the problems can be solved using a specified compound.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/147,095 filed on May 5, 2016, which is a continuation of U.S.application Ser. No. 14/727,323 filed on Jun. 1, 2015, which is acontinuation of U.S. application Ser. No. 13/995,879 filed on Sep. 4,2013, which is a national stage application filed under 35 U.S.C. §371of International Application No. PCT/JP2011/078999 filed Dec. 15, 2011,which claims the benefit of priority of Japanese Patent Application No.2010-287712 filed on Dec. 24, 2010, and the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a polymerizable compound-containingliquid crystal composition and a liquid crystal display device using thesame.

BACKGROUND ART

PSA (Polymer Sustained Alignment)-type liquid crystal display deviceshave a structure in which a polymer structure is formed in a cell inorder to control the pretilt angle of liquid crystal molecules, and havebeen progressively developed as liquid crystal display devices in viewof their rapid response and high contrast.

A PSA-type liquid crystal display device is manufactured by injecting apolymerizable compound-containing liquid crystal composition containinga polymerizable compound and a liquid crystal compound betweensubstrates, and polymerizing the polymerizable compound under acondition where liquid crystal molecules are aligned by applying avoltage, thereby fixing the alignment of the liquid crystal molecules.In the PSA-type liquid crystal display device, impurities and a changein alignment of the liquid crystal molecules (change in pretilt angle)are known as causes for image sticking as a display defect.

A cause for a change in pretilt angle is that in a configuration of aliquid crystal display device using a soft polymer which is a curedproduct of a polymerizable compound, a polymer structure is changed whenthe same pattern is continuously displayed for a long time, resulting ina change in pretilt angle. Therefore, a polymerizable compound whichforms a polymer having a rigid structure with no change in the polymerstructure is required.

In order to prevent image sticking by improving the rigidity of apolymer, it has been investigated to constitute a display device using apolymerizable compound having a structure of 1,4-phenylene group or thelike, which contains only a ring structure and a polymerizablefunctional group (refer to Patent Literature 1), or constitute a displaydevice using a polymerizable compound having a biaryl structure (referto Patent Literature 2). However, such polymerizable compounds have lowcompatibility with liquid crystal compounds and thus, when a liquidcrystal composition containing a polymerizable compound is prepared, theproblems such as precipitation of the polymerizable compound areproduced, leading to the need for improvement in compatibility with theliquid crystal composition.

Also, in order to prevent image sticking by improving the rigidity of apolymer, it has been proposed to constitute a display device using amixed liquid crystal composition containing a bifunctional polymerizablecompound and a tri- or higher-functional polymerizable compound, such asdipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, or thelike (refer to Patent Literature 3). However, dipentaerythritolpentaacrylate and dipentaerythritol hexaacrylate have no ring structurein the molecules thereof and thus have weak affinity for liquid crystalcompounds and weak force to regulate alignment, thereby causing theproblem of failing to achieve satisfactory alignment stability. Inaddition, polymerization of these polymerizable compounds requires apolymerization initiator to be added, and if a polymerization initiatoris not added, the polymerizable compounds remain after polymerization.

In addition, various combinations of liquid crystal compositions andpolymerizable compounds (refer to Patent Literature 4) are disclosed asmethods for improving switching speeds. However, a relation between thepretilt angle and switching speed is generally known, and a significantimprovement effect has not been confirmed. Since liquid crystalcompounds containing an alkenyl group and chlorine atom are used, adefective display is highly likely to be caused, resulting inimpracticality.

Therefore, there has been demand for a polymerizable compound-containingliquid crystal composition which simultaneously resolves the problems ofpreventing the occurrence of precipitation in a wide temperature rangeand the occurrence of image sticking, and achieving a fast switching,etc., and a liquid crystal display device using the liquid crystalcomposition.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No.2003-307720

PTL 2: Japanese Unexamined Patent Application Publication No.2008-116931

PTL 3: Japanese Unexamined Patent Application Publication No.2004-302096

PTL 4: WO 2010/084823

SUMMARY OF INVENTION Technical Problem

A problem to be solved by the present invention is to provide apolymerizable compound-containing liquid crystal composition whichcauses no precipitation within a wide temperature range and no failurein display characteristics, such as image sticking or the like, andwhich has low viscosity corresponding to fast switching, and to providea liquid crystal display device having excellent display quality withoutdisplay unevenness by using the polymerizable compound-containing liquidcrystal composition.

Solution To Problem

As a result of research of various polymerizable compounds and liquidcrystal compounds, the inventors of the present invention found that theabove-described problem can be resolved with a polymerizablecompound-containing liquid crystal composition containing apolymerizable compound and a liquid crystal compound each having aspecified structure, leading to the achievement of the presentinvention.

The present invention provides a polymerizable compound-containingliquid crystal composition including, as a first component, at least onepolymerizable compound represented by general formula (I),

(in the formula, R¹ and R² each independently represent any one offormulae (R-1) to (R-15) below,

and X¹ to X⁸ each independently represent a trifluoromethyl group, atrifluoromethoxy group, a fluorine atom, or a hydrogen atom, but atleast one of X¹ to X⁸ represents a fluorine atom); and as a secondcomponent, at least one compound represented by general formula (II),

(in the formula, R³ represents an alkyl group having 1 to 10 carbonatoms or an alkenyl group having 2 to 10 carbon atoms, in which at leastone hydrogen atom present in the group may be substituted by a fluorineatom, R⁴ represents an alkyl group or alkoxyl group having 1 to 10carbon atoms or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms, in which at least one hydrogen atom present in the groupmay be substituted by a fluorine atom, and m represents 0, 1, or 2).Also the present invention provides a liquid crystal display deviceusing the liquid crystal composition.

Advantageous Effects of Invention

Since the liquid crystal compound and the polymerizable compound in thepolymerizable compound-containing liquid crystal composition of thepresent invention have excellent compatibility with each other, anematic state can be maintained without sedimentation of the said liquidcrystal or polymerizable compounds even in long-term storage at a lowtemperature, thereby securing a very wide range of driving temperaturesin practical application. In addition, the liquid crystal composition ofthe present invention has a low viscosity and thus exhibits a fastswitching when used in a liquid crystal display device and can beapplied to 3D display. Further, the polymerizable compound of thepresent invention has an appropriate polymerization rate duringphotopolymerization, not an excessively high or low polymerization rate,and thus it is possible to achieve uniform and stable alignment controland provide a liquid crystal display device with little or no imagesticking, display unevenness, or the like. Therefore, the liquid crystalcomposition of the present invention is very useful.

Description of Embodiments

A polymerizable compound-containing liquid crystal composition of thepresent invention includes at least one polymerizable compoundrepresented by general formula (I) as a first component,

and at least one compound represented by general formula (II),

as a second component.

In the general formula (I) , R¹ and R² each independently represent anyone of formulae (R-1) to (R-15) below,

and X¹ to X⁸ each independently represent a trifluoromethyl group, atrifluoromethoxy group, a fluorine atom, or a hydrogen atom, but atleast one of X¹ to X⁸ represents a fluorine atom.

These polymerizable groups are cured by radical polymerization, radicaladdition polymerization, cation polymerization, or anion polymerization.In a polymerization method by ultraviolet irradiation, formula (R-1),formula (R-2), formula (R-4), formula (R-5), formula (R-7), formula(R-11), formula (R-13), or formula (R-15) is preferred, formula (R-1) orformula (R-2) is more preferred, and formula (R-2) is particularlypreferred.

In the general formula (I), X¹ to X⁸ each independently represent atrifluoromethyl group, a trifluoromethoxy group, a fluorine atom, or ahydrogen atom, but a fluorine atom is particularly preferred.

More preferred examples of a structure of a biphenyl skeleton in thegeneral formula (I) include those of formulae (I-11) to (I-14), and theformula (I-11) is particularly preferred.

Polymerizable compounds having skeletons represented by the formula(I-11) to the formula (I-14) have, after polymerization, optimumalignment regulating force for PSA-type liquid crystal display devicesand produce a good alignment state, thereby suppressing or preventingthe occurrence of display unevenness.

The polymerizable compound-containing liquid crystal composition of thepresent invention contains at least one polymerizable compoundrepresented by the general formula (I), but preferably contains 1 to 5compounds and more preferably 1 to 3 compounds. With a low content ofthe polymerizable compound represented by the general formula (I), thealignment regulating force for the liquid crystal composition isweakened. In contrast, with an excessively high content of thepolymerizable compound represented by the general formula (I), theenergy required for polymerization is increased to increase the amountof the polymerizable compound remaining unpolymerized, thereby causing adisplay defect. Therefore, the content is preferably 0.01 to 2.00% bymass, more preferably 0.05 to 1.00% by mass, and particularly preferably0.10 to 0.50% by mass.

In the general formula (II), R³ represents an alkyl group having 1 to 10carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein atleast one hydrogen atom present in the group may be substituted by afluorine atom, R⁴ represents an alkyl group or alkoxyl group having 1 to10 carbon atoms or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms, wherein at least one hydrogen atom present in the groupmay be substituted by a fluorine atom, and m represents 0, 1, or 2.However, R³ more preferably represents a linear group and an alkyl grouphaving 1 to 10 carbon atoms and particularly preferably an alkyl grouphaving 1 to 5 carbon atoms, R⁴ more preferably represents a linear groupand an alkyl group or alkoxyl group having 1 to 5 carbon atoms andparticularly preferably an alkoxyl group having 1 to 5 carbon atoms, andm more preferably represents 0 or 1.

The polymerizable compound-containing liquid crystal composition of thepresent invention contains at least one compound represented by thegeneral formula (II), but preferably contains 1 to 6 compounds and morepreferably 2 to 5 compounds. The content of the compound represented bythe general formula (II) is 5 to 35% by mass, more preferably 10 to 35%by mass, and particularly preferably 15 to 30% by mass.

In further detail, the general formula (II) is particularly preferablygeneral formula (II-A) or general formula (II-B).

(In the formulae, R⁵, R⁶, R⁷, and R⁸ each independently represent thesame meaning as R³.)

The polymerizable compound-containing liquid crystal composition of thepresent invention more preferably further contains at least one compoundrepresented by general formula (III).

(In the formula, R⁹ represents the same meaning as R³, and R¹⁰represents the same meaning as R⁴.)

The polymerizable compound-containing liquid crystal composition of thepresent invention contains at least one compound represented by thegeneral formula (III), but preferably contains 1 to 6 compounds and morepreferably 2 to 5 compounds. The content of the general formula (III) ispreferably 5 to 35% by mass, more preferably in a range of 10 to 30% bymass, and most preferably in a range of 15 to 30% by mass.

In further detail, the general formula (III) is particularly preferablygeneral formula (III-A).

(In the formulae, R¹¹ and R¹² each independently represent the samemeaning as R³.)

The liquid crystal compounds contained in the polymerizablecompound-containing liquid crystal composition of the present inventionhave no partial structure such as —O—O—, —O—S—, or —S—S—, in whichheteroatoms are directly bonded together. Also, the compounds preferablyinclude no compound having an alkenyl group, and side chains of allliquid crystal compounds are more preferably alkyl groups or alkoxygroups. In order to suppress or prevent the occurrence of displaydefects such as image sticking, nonuniformity in display, etc., each ofthe liquid crystal compounds preferably contains a cyclohexane ring, abenzene ring, or a fluorine-substituted benzene ring in its structure,but substitution with chlorine is undesired even if it is a halogenatom. The use of a chlorine-substituted liquid crystal compound isunpractical because it causes defective display.

A liquid crystal display device formed using the liquid crystalcomposition containing the compounds of the general formulae (I), (II),and (III) improves a fast switching characteristic due to low viscosityof the composition.

In the present invention, a nematic-isotropic liquid phase transitiontemperature (T_(ni)) is preferably 60° C. to 120° C., more preferably70° C. to 100° C. and particularly preferably 70° C. to 85° C. Inaddition, Δε at 25° C. is preferably −2.0 to −6.0, more preferably −2.5to −5.0, particularly preferably −2.5 to −3.5. Δn at 25° C. ispreferably 0.08 to 0.13 and more preferably 0.09 to 0.12. In furtherdetail, in response to a thin cell gap, An at 25° C. is preferably 0.10to 0.12, while in response to a thick cell gap, Δn at 25° C. ispreferably 0.08 to 0.10. The viscosity at 20° C. is preferably 10 to 30mPa·s, more preferably 10 to 25 mPa·s, and particularly preferably 10 to20 mPa·s.

The polymerizable compound-containing liquid crystal composition of thepresent invention may further contain, besides the above-describedcompounds, a usual nematic liquid crystal, smectic liquid crystal,cholesteric liquid crystal, antioxidant, ultraviolet absorber,polymerizable monomer, or the like. For example, compounds representedby general formulae (IV-1) to (IV-12) may be contained.

Although polymerization proceeds in the polymerizablecompound-containing liquid crystal composition of the present inventioneven in the absence of a polymerization initiator, the composition maycontain the polymerization initiator for promoting polymerization.Examples of the polymerization initiator include benzoin ethers,benzophenones, acetophenones, benzylketals, acylphosphine oxides, andthe like. In order to improve storage stability, a stabilizer may beadded to the liquid crystal composition of the present invention.Examples of the stabilizer which can be used include hydroquinones,hydroquinone monoalkyl ethers, tert-butylcatechols, pyrogallols,thiophenols, nitro compounds, β-naphthylamines, β-naphthols, nitrosocompounds, and the like. The polymerizable compound-containing liquidcrystal composition of the present invention is useful for a liquidcrystal display device, particularly a liquid crystal display device foractive matrix driving, and can be used for a liquid crystal displaydevice for a PSA mode, PSVA mode, VA-mode, IPS mode, or ECB mode.

The polymerizable compound-containing liquid crystal composition of thepresent invention is imparted with a liquid crystal aligning abilitythrough ultraviolet irradiation polymerization of the polymerizablecompound contained in the liquid crystal composition, and is used for aliquid crystal display device in which the amount of transmitted lightis controlled by using birefringence of the liquid crystal composition.The liquid crystal composition is useful for liquid crystal displaydevices such as AM-LCD (active matrix liquid crystal display device), TN(twisted nematic liquid crystal display device), STN-LCD (super twistednematic liquid crystal display device), OCB-LCD and IPS-LCD (in-planeswitching liquid crystal display device), and particularly useful forAM-LCD. The liquid crystal composition can be used for a transmissive orreflective liquid crystal display device.

Two substrates of a liquid crystal cell used in the liquid crystaldisplay device can be made of a transparent material with flexibility,such as glass or plastic, and one of the substrates may be made of anopaque material such as silicon or the like. A transparent substrateincluding a transparent electrode layer can be formed by, for example,sputtering indium-tin oxide (ITO) on a transparent substrate such as aglass plate.

A color filter can be formed by, for example, a pigment dispersionmethod, a printing method, an electrodeposition method, or a dyeingmethod. The pigment dispersion method is described as an example of themethod for forming the color filter. A curable colored composition for acolor filter is applied to the transparent substrate, patterned, andthen cured by heating or light irradiation. This process is performedfor each of the three colors of red, green, and blue, forming pixelportions for the color filter. Further, a pixel electrode provided withan active element such as TFT, a thin-film diode, a metal insulator, ametal resistivity element, or the like may be provided on the substrate.

The substrates are opposed to each other so that the transparentelectrode layers face inward. In this case, the distance between thesubstrates may be adjusted using a spacer so that the thickness of theresultant light control layer is preferably 1 to 100 μm and morepreferably 1.5 to 10 μm. When a polarizing plate is used, the product ofrefractive index anisotropy Δn of the liquid crystal and cell thicknessd is preferably adjusted to maximize the contrast. In addition, when twopolarizing plates are provided, the polarizing axis of each of thepolarizing plates can be adjusted to improve the viewing angle andcontrast. Further, a retardation film can be used for widening theviewing angle. Examples of the spacer include glass particles, plasticparticles, alumina particles, photoresist materials, and the like. Then,a sealing agent such as an epoxy-based thermosetting composition isscreen-printed on each of the substrates provided with a liquid crystalinjection port, the substrates are bonded together, and the sealingagent is thermally cured by heating.

As a method for holding the polymerizable compound-containing liquidcrystal composition between the two substrates, a usual vacuum injectionmethod or an ODF method can be used.

A preferred method as a method for polymerizing the polymerizablecompound is to polymerize the compound by irradiation with one type orcombination of two or more types of active energy rays such asultraviolet rays, electron beams, and the like, or by successiveirradiation with these types of active energy rays because a properpolymerization rate is desired for achieving good alignment performancefor the liquid crystal. In the use of ultraviolet rays, a polarizedlight source or an unpolarized light source may be used. When thepolymerizable compound-containing liquid crystal composition ispolymerized in the state of being held between the two substrates, atleast the irradiation-side substrate must be imparted with propertransparency for the active energy rays. Another method may be used, inwhich after a specified portion is polymerized by light irradiationusing a mask, the alignment state of an unpolymerized portion is changedby changing the condition such as an electric field, a magnetic field,or temperature, followed by further polymerization through irradiationwith active energy rays. In particular, ultraviolet exposure ispreferably performed with an alternating current electric field appliedto the polymerizable compound-liquid crystal composition. The appliedalternating current electric field is preferably has a frequency of 10Hz to 10 kHz and more preferably a frequency of 60 Hz to 10 kHz, and thevoltage is selected depending to the desired pretilt angle of the liquidcrystal display device. That is, the pretilt angle of the liquid crystaldisplay device can be controlled by the applied voltage. In a MVA-modeliquid crystal display device, the pretilt angle is preferablycontrolled to 80 degrees to 89.9 degrees from the viewpoint of alignmentstability and contrast.

The temperature of irradiation preferably falls in a temperature rangewhere the liquid crystal state of the liquid crystal composition of thepresent invention is maintained. Polymerization is preferably performedat a temperature close to room temperature, i.e., typically atemperature of 15 to 35° C. As a lamp for emitting ultraviolet rays, ametal halide lamp, a high-pressure mercury lamp, an ultrahigh-pressuremercury lamp, or the like can be used. In addition, the wavelength ofirradiating ultraviolet rays preferably falls in an ultravioletwavelength region excluding an absorption wavelength region of theliquid crystal composition, and, if required, ultraviolet rays may bepartially cut off. The intensity of the irradiating ultraviolet rays ispreferably 0.1 mW/cm² to 100 W/cm² and more preferably 2 mW/cm² to 50W/cm². The energy of the irradiating ultraviolet rays can beappropriately adjusted, but is preferably 10 mJ/cm² to 500 J/cm² andmore preferably 100 mJ/cm² to 200 J/cm². The intensity may be changedduring ultraviolet irradiation. The time of ultraviolet irradiation isappropriately selected depending on the intensity of the irradiatingultraviolet rays, but is preferably 10 seconds to 3600 seconds and morepreferably 10 seconds to 600 seconds.

EXAMPLES

The present invention is described in further detail below withreference to examples, but the present invention is not limited to theseexamples. In a composition of each of the examples and comparativeexamples, “%” represents “% by mass”.

In the examples, the measured characteristics are as follows.

T_(ni): nematic-isotropic liquid phase transition temperature (° C.)

Δn: refractive index anisotropy at 25° C.

Δε: dielectric constant anisotropy at 25° C.

η: viscosity at 20° C. (mPa·s)

EXAMPLE 1

A polymerizable compound-containing liquid crystal composition preparedand physical property values thereof are given below.

The polymerizable compound-containing liquid crystal compositiondescribed in Example 1 contained 99.85% of the above-described liquidcrystal composition and 0.15% of a polymerizable compound represented bygeneral formula (I-11), and showed T_(ni): 75.5° C., Δn: 0.107, Δε:−3.0, and η: 17.5 mPa·s.

The polymerizable compound-containing liquid crystal composition wasinjected, by a vacuum injection method, into a cell with ITO having acell gap of 3.5 μm and a polyimide alignment film applied thereto forinducing homeotropic alignment. The liquid crystal composition wasirradiated with ultraviolet rays for 600 seconds through a filter forcutting off ultraviolet rays of 320 nm or less while a rectangular waveof a frequency of 1 kHz and 1.8 V was applied using a high-pressuremercury vapor lamp adjusted so that the intensity of irradiation of acell surface was 15 mW/cm² to polymerize the polymerizable compound inthe polymerizable compound-containing liquid crystal composition,thereby producing a homeotropic liquid crystal display device. Theliquid crystal display device (PSVA mode) showed high contrast and wascapable of fast switching. Also, the alignment regulating force of thepolymerizable compound for the liquid crystal compound was confirmed bymeasuring a pretilt angle.

EXAMPLE 2

A polymerizable compound-containing liquid crystal composition preparedand physical property values thereof are given below.

The polymerizable compound-containing liquid crystal compositiondescribed in Example 2 contained 99.8% of the above-described liquidcrystal composition and 0.2% of a polymerizable compound represented bygeneral formula (I-11), and showed T_(ni): 75.5° C., Δn: 0.107, Δε:−3.0, and η: 17.5 mPa·s.

A liquid crystal display device (PSVA mode) using the polymerizablecompound-containing liquid crystal composition showed high contrast andwas capable of fast switching. Also, the alignment regulating force ofthe polymerizable compound for the liquid crystal compound was confirmedby measuring a pretilt angle.

EXAMPLE 3

A polymerizable compound-containing liquid crystal composition preparedand physical property values thereof are given below.

The polymerizable compound-containing liquid crystal compositiondescribed in Example 3 contained 99.65% of the above-described liquidcrystal composition and 0.35% of a polymerizable compound represented bygeneral formula (I-11), and showed T_(ni): 75.4° C., Δn: 0.107, Δε:−3.0, and η: 17.5 mPa·s.

A liquid crystal display device (PSVA mode) using the polymerizablecompound-containing liquid crystal composition showed high contrast andwas capable of fast switching. Also, the alignment regulating force ofthe polymerizable compound for the liquid crystal compound was confirmedby measuring a pretilt angle.

EXAMPLE 4

A polymerizable compound-containing liquid crystal composition preparedand physical property values thereof are given below.

The polymerizable compound-containing liquid crystal compositiondescribed in Example 4 contained 99.6% of the above-described liquidcrystal composition and 0.4% of a polymerizable compound represented bygeneral formula (I-11), and showed T_(ni): 75.4° C., Δn: 0.107, Δε:−3.0, and η: 17.5 mPa·s.

A liquid crystal display device (PSVA mode) using the polymerizablecompound-containing liquid crystal composition showed high contrast andwas capable of fast switching. Also, the alignment regulating force ofthe polymerizable compound for the liquid crystal compound was confirmedby measuring a pretilt angle.

Comparative Example 1

The polymerizable compound-containing liquid crystal compositionprepared and physical property values thereof are given below.

A polymerizable compound-containing liquid crystal composition describedin Comparative Example 1 contained 99.8% of the liquid crystalcomposition of Example 1 and 0.2% of a polymerizable compound describedin Japanese Unexamined Patent Application Publication No. 2003-307720.

Each of the liquid crystal compositions of Examples 1 to 4 andComparative Example 1 was subjected to a low-temperature storage test.As a result, Examples 1 to 4 maintained a nematic state at a temperatureof any one of −40° C. and −25° C. for 2 or 3 weeks, while ComparativeExample 1 maintained a nematic state only for 1 week, and precipitationwas observed in the second week. This confirmed that Examples 1 to 4maintain a nematic state within a wide temperature range and maintainstability at a low temperature over a long period of time of 2 or 3times that of Comparative Example 1 and are very useful polymerizablecompound-containing liquid crystal compositions.

TABLE 1 Low-temperature storage test −40° C. −25° C. Example 1 Nematicstate for 3 weeks Nematic state for 3 weeks Example 2 Nematic state for3 weeks Nematic state for 3 weeks Example 3 Nematic state for 3 weeksNematic state for 3 weeks Example 4 Nematic state for 2 weeks Nematicstate for 3 weeks Comparative Nematic state for 1 week Nematic state for1 week Example 1

Comparative Example 2

A polymerizable compound-containing liquid crystal composition preparedand physical property values thereof are given below.

The polymerizable compound-containing liquid crystal compositiondescribed in Comparative Example 2 contained 99.8% of the liquid crystalcomposition not containing compounds represented by the general formulae(II-A) and (II-B) of the present invention and 0.2% of a polymerizablecompound described in Japanese Unexamined Patent Application PublicationNo. 2003-307720, and showed T_(ni): 76.4° C., Δn: 0.107, Δε: −2.9, andη: 21.2 mPa·s. It is easily supposed that since the viscosity issignificantly increased, the switching speed is significantly worsenedwhen a liquid crystal device is manufactured. A liquid crystal displaydevice (PSVA mode) using the polymerizable compound-containing liquidcrystal composition showed high contrast but showed a low switchingspeed and impracticality. Also, the alignment regulating force of thepolymerizable compound for the liquid crystal compound was confirmed bymeasuring a pretilt angle.

Example 5

A polymerizable compound-containing liquid crystal composition preparedand physical property values thereof are given below.

The polymerizable compound-containing liquid crystal compositiondescribed in Example 5 contained 99.8% of the above-described liquidcrystal composition and 0.2% of a polymerizable compound represented bygeneral formula (I-11), and showed T_(ni): 76.4° C., Δn: 0.092, Δε:−2.9, and η: 18.6 mPa·s.

A liquid crystal display device (PSVA mode) using the polymerizablecompound-containing liquid crystal composition showed high contrast andwas capable of fast switching. Also, the alignment regulating force ofthe polymerizable compound for the liquid crystal compound was confirmedby measuring a pretilt angle.

Example 6

A polymerizable compound-containing liquid crystal composition preparedand physical property values thereof are given below.

The polymerizable compound-containing liquid crystal compositiondescribed in Example 6 contained 99.8% of the above-described liquidcrystal composition and 0.2% of a polymerizable compound represented bygeneral formula (I-11), and showed T_(ni): 76.3° C., Δn: 0.091, Δε:−2.7, and η: 18.4 mPa·s.

A liquid crystal display device (PSVA mode) using the polymerizablecompound-containing liquid crystal composition showed high contrast andwas capable of fast switching. Also, the alignment regulating force ofthe polymerizable compound for the liquid crystal compound was confirmedby measuring a pretilt angle.

Therefore, it was confirmed that the polymerizable compound-containingliquid crystal composition of the present invention maintains a nematicstate over a wide temperature range, and the liquid crystal displaydevice using the liquid crystal composition exhibits fast switching.

Industrial Applicability

The present invention is useful as a liquid crystal composition for aliquid crystal display device.

What is claimed is:
 1. A polymerizable compound-containing liquidcrystal composition comprising, as a first component, at least onepolymerizable compound represented by general formula (I),

(in the formula, R¹ and R² each independently represent any of formulae(R-1) to (R-15) below,

and X¹ to X⁸ each independently represent a trifluoromethyl group, atrifluoromethoxy group, a fluorine atom, a chlorine atom, or a hydrogenatom, but at least one of X¹ to X⁸ represents a fluorine atom) and, atleast one compounds represented by general formulae (IV-8)

(in the formula, R³ represents an alkyl group having 1 to 10 carbonatoms, wherein at least one hydrogen atom present in the group may besubstituted by a fluorine atom, R⁴ represents an alkyl group or alkoxylgroup having 1 to 10 carbon atoms, wherein at least one hydrogen atompresent in the group may be substituted by a fluorine atom).
 2. Apolymerizable compound-containing liquid crystal composition, furthercomprising, as a second component, at least one compound represented bygeneral formula (IV-10),

(in the formula, R³ represents an alkyl group having 1 to 10 carbonatoms, wherein at least one hydrogen atom present in the group may besubstituted by a fluorine atom, R⁴ represents an alkyl group or alkoxylgroup having 1 to 10 carbon atoms, wherein at least one hydrogen atompresent in the group may be substituted by a fluorine atom).
 3. Thepolymerizable compound-containing liquid crystal composition accordingto claim 1, wherein the general formula (I) is any one of generalformula (I-1) to general formula (I-4),

(in the formulae, R¹ represents the same meaning as R¹ described inclaim 1, and R² represents the same meaning as R² described in claim 1).4. The polymerizable compound-containing liquid crystal compositionaccording to claim 1, wherein the general formula (I) is the generalformula (I-1).
 5. The polymerizable compound-containing liquid crystalcomposition according to claim 1, wherein in the general formula (I), R¹and R² are each independently formula (R-1) or (R-2).
 6. Thepolymerizable compound-containing liquid crystal composition accordingto claim 1, further comprising, as a third component, at least onecompound represented by general formula (III),

(in the formula, R⁹ represents the same meaning as R³ described in claim1, and R¹⁰ represents the same meaning as R⁴ described in claim 1). 7.The polymerizable compound-containing liquid crystal compositionaccording to claim 1, wherein the content of the compound represented bythe general formula (I) is 0.01% by mass to 2.0% by mass.
 8. Thepolymerizable compound-containing liquid crystal composition accordingto claim 1, wherein the content of the compound represented by thegeneral formula (III) is 5% by mass to 35% by mass.
 9. The polymerizablecompound-containing liquid crystal composition according to claim 1,wherein a dielectric constant anisotropy Δε at 25° C. is in a range of−6.0 to −2.0, a refractive index anisotropy Δn at 25° C. is in a rangeof 0.08 to 0.13, a viscosity (η) at 20° C. is in a range of 10 to 30mPa·s, and a nematic-isotropic liquid phase transition temperature(T_(ni)) is in a range of 60° C. to 120° C.
 10. A liquid crystal displaydevice comprising the polymerizable compound-containing liquid crystalcomposition according to claim
 1. 11. The liquid crystal display deviceaccording to claim 10, wherein the liquid crystal display device is anactive matrix drive liquid crystal device.
 12. The crystal displaydevice according to claim 10, wherein the liquid crystal display deviceis of a PSA mode, a PSVA mode, a VA mode, an IPS mode, or an ECB mode.13. The liquid crystal display device according to claim 10, wherein apretilt angle is 85 to 89.9 degrees.